To investigate the production of useful phenols from plant resources, we examined the metabolism of cinnamic acid derivatives by a wood-rotting fungus, Schizophyllum commune. Four cinnamic acid derivatives (cinnamic, p-coumaric, ferulic, and sinapic acids) were tested as substrates. Two main reactions, reduction and cleavage of the side chain, were observed. Reduction of the side chain was confi rmed in cinnamic acid and p-coumaric acid metabolism. The side chain cleavage occurred in p-coumaric acid and ferulic acid metabolism but the initial reactions of these acids differed. Sinapic acid was not metabolized by S. commune. p-Hydroxybenzaldehyde accumulation was observed in the culture to which p-coumaric acid was added. This suggests that S. commune is a useful agent for transforming p-coumaric acid into p-hydroxybenzaldehyde. S. commune has the potential to release and metabolize cinnamic acid derivatives esterifi ed or etherifi ed to plant cell walls. It is a white-rot fungus and enables the release of etherifi ed cinnamic acid derivatives during lignin degradation by ligninolytic enzymes such as laccase and peroxidases. It produces ferulic acid esterase (MacKenzie and Bilous, 1988) and p-coumaric acid esterase (unpublished data), and releases cinnamic acid derivatives esterifi ed to xylans in plant cell walls. Furthermore, it secretes highly active extracellular cellulolytic and xylanolytic enzymes during plant biomass degradation (Haltrich and Steiner, 1994) and it has the ability to enhance the accessibility of ligninolytic enzymes and cinnamic acid esterases to plant cell walls. Thus, S. commune is expected to independently convert the cinnamic acid derivatives bound to plant cell walls. KeyVarious kinds of cinnamic acid derivatives are found in plant biomass. To use S. commune for the bioconversion of these acid derivatives, it is necessary to study its metabolic potential. In this study, we investigated the metabolic mechanism of 4 cinnamic acid derivatives by identifying their metabolic products. Materials and MethodsStrain and cultivation methods. Schyzopyllum commune (Kyoto Prefectural University Forestry Collection (KPUF) 0588) was used in this study. The basal medium was prepared according to Kirk et al. (1978) and contained 1% glucose and 1 mM ammonium tartrate as carbon and nitrogen sources, respectively.Conversion test. S. commune was inoculated onto agar culture containing Kirk s basal media, 1% glucose and 1 mM ammonium tartrate in a 90-mm petri dish and cultivated at 28 C for 1 week. A mycelium plug (6 mm in diameter) was inoculated with 30 ml of liquid medium in 100 ml Erlenmeyer fl asks and incubated (stationary) at 28 C. S. commune culture was incubated for 3 days before adding 3 cinnamic acid derivatives, namely p-coumaric acid, ferulic acid, and sinapic acid, and for 5 days when cinnamic acid was added. The cinnamic acid derivatives were aseptically added to the liquid cultures (fi nal concentration: 1.0 mM). The cinnamic acid derivatives tested were cinnamic acid, p-coumaric acid (4-hyd...